Elastic Support:
An Elastic Support defines an elastic foundation between the selected faces of a part or assembly and the ground. The Elastic Support is based on a Foundation Stiffness, which is defined as the pressure required to produce a unit normal deflection of the foundation. Elastic Support applies flexible frictionless support to a face.
Elastic support is used to represent foundation stiffness. For example; Elastic support can be used to model piles which are used to support LNG tanks, Another example is base frame or skid are mounted on foundations, which can be model using elastic supports in FEA.
How to Model Elastic Support?
Elastic supports are modeled using stiffness in normal and tangential or shear directions. Many FEA software provides elastic support as boundary conditions.
In case of ANSYS workbench, elastic support is used to act in a direction normal to selected faces on a body. It does not provide any stiffness that acts in a direction that is tangent to faces. An elastic foundation that will act in both normal and tangential directions on selected faces can be created via an APDL Commands Object that is inserted into the Outline of a model. The elastic support actions are defined by using bonded contact and absolute values for contact stiffness FKN (normal stiffness) & FKT(Tangential Stiffness) are defined to contact elements.
Elastic support is modelled just selecting required face of the body and defining the respective foundation stiffness value.
Different between Elastic Support and Spring ?
Spring is an elastic element that regains its undeformed shape after a compression or extension load is removed. It is used to represent the actual spring modeling behavior. While Elastic support is kind of boundary condition (Support) to represent foundation stiffness
Spring is modelled by selecting two points (body to body or body to ground), by defining longitudinal stiffness and longitudinal damping value. While Elastic Support is modelled by selecting the required face of the body.
Spring stiffness unit is N/m while elastic support unit is N/mm3.
Summary:
- Elastic support is used to define foundation stiffness.
- Elastic support is available in all commercial FEA software and it unit is N/mm3.
- In ANSYS Mechanical, tangential stiffness value for elastic support is defined through the APDL command script.
- Spring is elastic element while elastic support is foundation stiffness.